U.S. Pat. No. 4,299,012 A discloses an open hose clamp having mutually overlapping band ends, of which the outer band part comprises, starting from the outer band end, an opening, an ear-shaped formation for tightening the clamp by shortening the band length, and a channel extending in the longitudinal direction of the band, while the inner band part comprises, starting from the inner band end, a tongue, which engages in the channel when the clamp is in the tightened state, an area spanning the area under the ear-shaped formation, and a hook for insertion into the opening.
By virtue of the fact that its inner surface has no gaps or steps in the tightened state and thus supports the hose at all points of the circumference, the known hose clamp has also proven useful for fastening thin, hard hoses on pipe nipples. Tightening is carried out using a formation which in the technical field has become known as the xe2x80x9cOetiker earxe2x80x9d and which, after one or more hooks provided on the inner band part have been inserted into corresponding openings in the outer band part, is constricted with the aid of grippers or a similar tool in order to reduce the diameter of the hose clamp and bring about a sufficient sealing pressure between hose and pipe nipple.
In the case of the known hose clamp, when it is in the tightened state, the tongue provided on the inner band end engages in a tongue channel which is provided in the outer band part and which is formed by forming two parallel slots extending in the band direction and pressing the central section out. This central section closes the tongue channel from outside and prevents the tongue from emerging beyond the circumference of the band.
Similar designs are known from EP 0,697,554 A1, DE 3,818,953 A1 and U.S. Pat. No. 4,711,001 A. In the clamp according to DE 3,818,953 A1, the tongue channel is designed simply as a depression in the outer band part. In the clamp according to U.S. Pat. No. 4,711,001 A, the tongue channel is covered off from the outside by a central part which is formed by two longitudinal cuts and punched free from the band material at the end corresponding to the tongue tip.
U.S. Pat. No. 5,177,836 A and U.S. Pat. No. 5,339,496 A disclose open hose clamps which, near the inner band end, have a guide lug which protrudes outwardly through a slot in the outer band part. In both cases, the inner band part, except for the narrow guide lug, lies on the inner surface of the outer band part.
U.S. Pat. No. 3,981,049 A discloses another open hose clamp which, to permit engagement of a tightening tool, comprises a ladder-like arrangement of openings in the inner band part, and a pulling hook on the outer band part. The openings are accessible to the tightening tool via a slot which is provided in the outer band part and which at the same time serves for guiding a tongue arranged at the inner band end.
A general object of the invention is to at least in part remedy the disadvantages of hose clamps according to the prior art. A more specific object of the invention can be regarded as being to provide a hose clamp which, while being inexpensive to manufacture, can be used in as many different ways as possible.
To achieve this object, the invention provides an open hose clamp with mutually overlapping band ends, of which the outer band part comprises, starting from the outer band end, an opening, an ear-shaped formation for tightening the clamp by shortening the band length, and a channel extending in the longitudinal direction of the band, while the inner band part comprises, starting from the inner band end, a tongue which engages in the channel when the clamp is in the tightened state, an area spanning the area under the ear-shaped formation, and a hook for insertion into the opening, the channel being designed as an open aperture which is wider than the tongue, and the tongue comprising an attachment projecting outwards through the aperture.
In the hose clamp according to the invention, there is none of the friction which occurs between tongue and channel in the prior art and which makes tightening the hose clamp difficult. In addition, the tongue remains accessible from the outside, both in the engaged state and in the tightened state of the clamp, so that the outwardly projecting attachment provided on it is available for handling the clamp and for improving its function.
The attachment on the tongue preferably has substantially the width of the aperture. The resulting guide function ensures that the tongue is aligned with the tongue channel even before tightening and in particular during tightening of the hose clamp and is thus kept centred with respect to the width of the hose clamp.
The attachment can have flanges bent outwards in the radial direction of the hose clamp on both sides of the tongue. This structure gives the attachment high strength, in particular in the circumferential direction.
According to an alternative, the attachment includes an outwardly bent end of the tongue. This embodiment is particularly easy to produce, and the strength can be increased by the fact that the attachment is a fold formed from the material of the tongue.
In any case, it is favourable if the side of the attachment on the tongue remote from the outer band end forms an angle of at most 90xc2x0 with the circumferential direction of the hose clamp, so that the hose clamp is reliably locked in the engaged state of maximum diameter.
In one embodiment of the invention, the tongue comprises a step which protrudes inwards, as seen from the inner band end, which has a height substantially equal to the thickness of the band material, and which lies in the area of the aperture when the hose clamp is in the tightened state. In this case, the outer band part can comprise, near the aperture, a step which protrudes inwards, as seen from the outer band end, and which has a height substantially equal to the thickness of the band material. These features are advantageous for obtaining a hose clamp which, in the tightened state, has an inner surface which is free from gaps and steps over the whole circumference.
The tightened hose clamp can be easily reopened if the outer band part comprises an outwardly protruding formation arranged on the side of the aperture remote from the outer band end. The formation and the attachment on the tongue on the outer band part constitute points of engagement for a suitable tool.
In order to prevent this tool from slipping, it is advantageous if the side of the formation remote from the outer band end forms an angle of at most 90xc2x0 with the circumferential direction of the hose clamp. In this case, the hose clamp can be expediently opened with the same gripper-type tool as is used to close the Oetiker ear when tightening the hose clamp.
The production tool can be simplified if the formation is designed as a hook which has the same shape as the hook provided on the inner band part.
In a further embodiment, the outer band part has an undulated band area between the opening and the ear, which band area preferably comprises a plurality of individual waves. This design makes it possible to use the same hose clamp for different diameters. At the same time, the elastic area of the hose clamp is increased. Since the undulation is situated in the outer band part between the opening and the ear, it is also spanned, like the ear itself, by the entire width of the inner band part, so that the continuous closed inner surface of the hose clamp is maintained also in this area.
With a given band material, the modulus of elasticity can be increased or decreased by providing the undulated band area is with a slot or bead in the longitudinal direction of the band.
Advantageously, the attachment forms substantially the whole length of the tongue and is bent back around the edge of the aperture facing the outer band end. In this way, a possibly excessive protrusion of the tongue is avoided, and at the same time an additional means of securing the closed and tightened hose clamp is obtained.
In a further embodiment, the inner band part comprises, in the area adjoining the tongue in the longitudinal direction of the band, two beads into which two beads adjoining the aperture in the outer band part engage when the hose clamp is in the tightened state, and the end of each bead remote from the inner band end merges with decreasing height into the inner surface of the outer band part. In this way it is possible to shorten the length of the tongue and of the overlapping area, thus reducing the overall length of the band.